1. Field of the Invention:
This invention relates to a metering feeder for a variety of liquids, and more specifically to an apparatus most suitable for feeding a rated amount of such a liquid that its viscosity increases considerably when a certain magnitude of compression and shear forces (may hereinafter be referred to simply as "liquid") are applied thereto. As an example of such a liquid, a "TEFLON" emulsion which is useful as a particle binder may be mentioned.
2. Description of the Prior Art:
No satisfactory metering feeders of the above type have yet been marketed due in part to little demand for such feeders from the industry. Whenever a need for feeding liquid at a constant low rate arises, it is now managed to meet such need with a general metering feeder for fluid such as plunger pump, trochoid pump, vane pump or peristaltic pump although such a general metering feeder may not be able to derive a fully satisfactory result.
Among such conventional metering feeders, the plunger, vane and trochoid pumps, each induces compression and shear forces between its rotating members and/or in a spacing between its rotating member and casing upon feeding a liquid, thereby making the viscosity of the liquid considerably greater and making it impossible, needless to say, not only to feed the liquid at a predetermined, constant, small rate but also even to feed the liquid in a rated amount per unit time along the passage of its operation. For example, in the case of the above-referred to "TEFLON" emulsion, "TEFLON" is fibrillated into solid substances under the action of compression and shear forces and any subsequent metered feeding becomes infeasible.
On the other hand, a peristaltic pump performs drawing and delivery of liquid by continuously squeezing out liquid in flowing a tube by means of rotors. Here, the viscosity of the liquid also increases to a considerable extent and the tube is eventually clogged after a predetermined operation time. (due to the formation of solid substances when the liquid is a "TEFLON" emulsion), thereby also making further metered feeding impossible.
Whenever such prior art pumps developed such a problem, it has been possible to make them usable again by disassembling them and removing gumming, solid substances and the like stuck on the casings and rotating members thereof.
Accompanying an expansion in the technical field in which such liquids are handled as raw materials, there has recently been a strong demand for the development of an apparatus which can perform a continuous rated supply (particularly, small and rated supply) of liquid over a long time period.